Enhancing Li-S Battery Performance Through Low-Concentration Electrolytes with Organic Se/Te Co-Additives to Address...

Area of Science:

• Electrochemistry
• Materials Science
• Energy Storage

Background:

• Lithium-sulfur (Li-S) batteries are promising for high energy density storage but suffer from low sulfur utilization and poor rate capability.
• Electrolyte engineering is crucial for improving lithium polysulfide (LiPS) conversion kinetics, yet balancing energy and power density remains a challenge.

Purpose of the Study:

• To enhance the performance of Li-S batteries by addressing LiPS solubility limitations and kinetic bottlenecks.
• To develop a novel electrolyte system combining ultra-low concentration and a dual-functional additive for improved ionic conductivity and catalytic activity.

Main Methods:

• An ultra-low concentration electrolyte was combined with a dual-functional hybrid organic selenium/organic tellurium additive (DPDSe/DPDTe).
• The mixing ratio of DPDSe/DPDTe was adjusted to optimize the solvation structure and catalytic effects of the additive.
• Electrochemical performance, including specific capacity, sulfur utilization, rate capability, and cycling stability, was evaluated.

Main Results:

• The novel electrolyte system demonstrated significantly enhanced LiPS conversion kinetics and higher ionic conductivity.
• The Li-S battery achieved an initial specific capacity of 1103 mAh g^-1 at 0.5 C with 65.9% sulfur utilization.
• The battery retained 89.3% capacity after 100 cycles at 0.5 C and delivered 783 mAh g^-1 at 2 C.
• A pouch cell achieved a high energy density of 340 Wh kg^-1 at 0.5 C with stable cycling.

Conclusions:

• The synergistic effect of the low-concentration electrolyte and the dual-functional additive effectively overcomes LiPS solubility and kinetic limitations.
• This strategy provides a viable pathway for developing Li-S batteries with simultaneously high energy and high power density.
• The developed approach offers a promising solution for next-generation energy storage technologies.